Eric Knysz, 20, is accused of shooting Butterfield on Sept. 9, 2013 during a traffic stop in rural Mason County. Butterfield, 43, died later that night during emergency surgery.

Friday marked Day 4 of the hearing, and now jurors are getting an inside look at the complex investigation into what happened.

The jury heard from the police officers — again focusing on the more technical side of this case, not just the crime but also the alleged cover-up.

We heard from an officer who analyzed a napkin found in a burn barrel at Knysz’ home. That napkin was believed to have been used to clean off Butterfield’s blood from the truck Knysz was driving during the traffic stop when police said he fatally shot Butterfield.

We heard from forensic scientists who testified the blood on that truck was indeed Trooper Butterfield’s.

Later Friday we expect to hear from more of those who analyzed the evidence in this case, and then some of the people who know the most about what happened — namely star witness and Knysz’ wife.Tweets by @LeonHendrix